In continuous fluid-flow manufacturing industries such as the production of petrochemicals, a continuous flow of a fluid is periodically sampled and analyzed by an automated sampling-and-analysis system. The results of the analysis are used to control process operating parameters through a feedback control system. The present invention is concerned with the sampling and fluid control apparatus, rather than the analysis apparatus or the feedback control system.
In the sampling-and-analysis system, valves, regulators, gauges, flow indicators, and other fluid components are linked together to provide a sample of the process fluid flow to the analyzer and then to return the sample back to the process flow. The earliest sampling and analysis systems used conventional discrete fluid components linked by piping. These systems extract a relatively large volume of fluid in each sample, and the distances that the fluid must flow through the system are relatively large. Consequently, the sampling lag time is relatively long, which is undesirable from the standpoint of achieving good process control. These discrete-component systems have relatively high installed cost and maintenance cost.
The volume of fluid in the sample and the flow distance may be reduced by miniaturizing the system. In one approach, the fluid components are reduced in size as much as possible. The miniature fluid components are mounted to a surface of a support structure that provides both mechanical support for the fluid components and also mechanical and fluid interconnection between the fluid components.
This surface-mount fluid-flow system has the potential to reduce installed cost and maintenance cost for flow sampling, and a number of surface-mount systems have been proposed. However, the available systems have a number of shortcomings. Most installations are one-of-a-kind or require only a few of the same type of sampling-and-analysis systems, so that most installations are of a custom or semi-custom type. The available systems typically involve a large number of components, and/or expensive custom machining of components for each installation, and/or high assembly costs. The design procedures are also complex. Additionally, in some systems there is a potential for cross contamination between fluid streams within the apparatus, of a type that cannot be readily detected.
There is a need for an improved fluid-flow system that overcomes these problems. Such a fluid-flow system is needed for the sampling-and-analysis field, and for other fields as well. The present invention fulfills this need, and further provides related advantages.